The invention relates to an airbag for a motor vehicle.
Such airbags are known and comprise an inflatable volume element for restraining occupants of the motor vehicle. The volume element comprises an inner space, into which a gaseous medium is introduced in order to move the volume element from a storage position into a restraint position to restrain the occupants. In order to guarantee optimum protection of occupants it is advantageous to inflate the volume element in a particularly short time. The faster it is inflated from its storage position into its restraint position the better the restraining function, as it can then take up a particularly large volume in an inner space of the motor vehicle in order to restrain the occupants.
Exemplary embodiments of the present invention are directed to an airbag for a motor vehicle that guarantees very good occupant protection.
In accordance with exemplary embodiments of the present invention an airbag for a motor vehicle comprises a housing and at least one restraint element comprising at least one receiving area for a gaseous medium, in particular air, said restraint element being movable in case of an accident-related force impact of the motor vehicle from a storage position within the housing into a restraint position through inflow of the medium into the receiving area. This means that the restraint element in the storage position is housed at least in areas in the housing, from which it can be moved from the storage position into the restraint position, in which the restraint element takes up a particularly large volume in an inner space of the motor vehicle in order to thus guarantee a very good restraint of occupants in case of an accident.
If at least one wall of the housing comprises at least one inflow opening for the medium, through which the medium can flow into the receiving area of the restraint element, the restraint element can thereby be moved particularly quickly, i.e., in a particularly short time, from its storage position into its restraint position. This means that the restraint element, in case of an accident, can take up a particularly large space or a particularly large volume in the inner space of the motor vehicle in order to protect occupants from collision with hard components causing injury. This has a particularly good effect upon occupant protection in the motor vehicle. The probability of the occupants suffering serious injuries is thus lower.
The restraint element can thereby be designed as a large, cohesive air sack that can be inflated by medium flowing into the receiving area for movement from the storage position into the restraint position. The medium can be actively blown into the receiving area, for example, by means of a gas generator. Alternatively, the medium can be sucked into the receiving area through the airbag unfolding upon movement from the storage position into the receiving position.
In addition, the restraint element can be formed by a lattice-like supporting structure, which is optionally provided with a shell at least in areas, whereby the receiving area is formed. The lattice-like supporting structure is thereby formed, for example, from a plurality of tube elements that also have a respective further receiving area, into which a medium can flow, wherein the medium is actively introduced, in particular blown, for example by means of a gas generator, into the respective further receiving area of the tube elements. Through the inflation of the tube elements the lattice-like supporting structure unfolds from the storage position into the restraint position and takes up a particularly large volume in the inner space of the motor vehicle. A so-called lattice-like bag with this supporting structure has the advantage that the receiving areas of the tube elements in sum have a smaller total volume to be inflated than the whole supporting structure ultimately takes up in the inner space. This lattice-like bag can thus take up a particularly high volume in the inner space, wherein a relatively small volume must be actively inflated. The receiving area of the airbag, formed by the supporting structure and possibly the shell, is thereby likewise filled with a gaseous medium, in particular ambient air, in order to achieve a good supporting effect of the lattice-like bag. Through the inflow opening in the wall of the housing the medium for this receiving area can flow particularly well and particularly rapidly into the receiving area of the restraint element formed by the supporting structure and optionally the shell, wherein this restraint element can likewise be moved particularly rapidly, i.e., in a short time, from the storage position into the restraint position. This is also particularly beneficial for occupant protection as the lattice-like bag can then prevent contact of the occupants with solid components that may cause injury in many cases. Through the inflow opening in the wall a possible under-pressure in the restraint element or in the receiving area, which could impede unfolding of the restraint element and thus lengthen an inflation time, can be prevented or at least reduced.
In an advantageous embodiment of the invention the airbag comprises at least one valve mechanism, by means of which a through-flow of the medium through the inflow opening can be adjusted. The valve mechanism preferably comprises at least one passage position exposing the inflow opening at least in areas, in which passage position the medium can flow into the receiving area. Likewise, the valve mechanism preferably has a closed position closing the inflow opening at least in areas, in which closed position an outflow of the medium from the receiving area is at least substantially prevented. Thus, the valve mechanism facilitates a particularly rapid movement of the restraint element from the storage position into the restraint position while also providing a very long useful life of the restraint element.
If, in case of an accident, an occupant comes into contact with the restraint element the receiving area is compressed, which causes or would cause initially an outflow of the medium from the receiving area. Due to the fact that the valve mechanism at least substantially prevents such an outflow in the closed position, the restraint element offers a certain useful life that depends upon a cross-section of the inflow opening that is opened or closed by the valve mechanism. The occupant can thus be protected in case of an accident and accelerations causing injuries can be reduced, as the medium can flow more slowly out of the receiving area than it can or could flow into the receiving area in case of movement of the restraint element into the restraint position. The inflow opening can also optionally be closed by the valve mechanism to such an extent that the medium can at least virtually no longer flow from the receiving area. It is understood that in case of a large cross-section of the inflow opening exposed by the valve mechanism more air can flow out of the receiving area. This results in a shorter useful life than in a case in which the valve mechanism exposes a smaller cross-section of the inflow opening. This results in a longer useful life of the restraint element.
The valve mechanism comprises for example at least one flap element, by means of which the inflow opening can be at least partially exposed or closed. The flap element is formed for example at least substantially as a film, as a textile layer and/or at least substantially from plastic. If the flap element exposes the inflow opening in the passage position it closes it at least in areas in the closed position, whereby it is supported for example on the wall of the housing delimiting the inflow opening. A failure of the flap element is thereby avoided.
It should be noted at this point that a ventilation, i.e., an inflow of the medium into the receiving area and possibly a valve mechanism, by means of which the through-flow of the medium through the inflow opening can be adjusted, is realized particularly in case of airbags without housing in such a way that at least one such inflow opening is integrated into a textile layer as a fabric of the airbag and thus directly into the restraint element, thus for example into the large cohesive airbag or the supporting structure or the shell thereof.